Interpretive Summary: Lettuce infectious yellows virus caused economic loss to melon and honeydew production in the desert southwest U.S. from 1981 through 1990. Breeding for resistance to this virus is made difficult by the need to use whiteflies to inoculate plants, the late development of symptoms, and similarity between yellowing due to the normal growth process and that caused by the virus. This report dewcribes procedures to verify infection of inoculated plants in greenhouse tests, and reports confirmation of resistance to this virus in a melon from India.

Technical Abstract:
Lettuce infectious yellows virus (LIYV) is a member of the Crinivirus Genus, Closteroviridae Family, a new group of whitefly-transmitted viruses that induce yellowing symptoms on wide range of cucurbit and non-cucurbits hosts. LIYV is transmitted efficiently by the sweetpotato whitelfy, Bemisia tabaci Gennadius (SPW). PI 313970 stood-out from the other potential sources for its consistently mild symptoms in response to infection by LIYV in a field test in 1990. Resistance to LIYV in PI 313970 was confirmed in greenhouse tests using controlled inoculations with the SPW. Uncertainty of symptom expression requires use of ELISA assays of inoculated plants, and may require serial transfer via sweetpotato whiteflies from inoculated melon plants to Chenopodium for verification based upon symptom expression and ELISA assay.